Which equation correctly relates Thevenin and Norton equivalents?

• A. V_th = R_N / I_N
• B. V_th = I_N^2 R_N
• C. V_th = I_N R_N
• D. V_th = I_N / R_N

Answer: (C)

The two standard ways to model the same network at its terminals—the Thevenin form (a voltage source V_th in series with a resistance) and the Norton form (a current source I_N in parallel with a resistance)—are equivalent when they share the same terminal behavior. The bridge between them is the open-circuit condition. With no load connected, the current source I_N flows through the parallel resistor R_N, generating a terminal voltage V_th equal to I_N times R_N. That gives the relation V_th = I_N R_N. Since the equivalent resistances must match (R_th = R_N), this single relation ties the Thevenin and Norton representations together. The other options mix units or the relationship and do not reflect how the two forms produce the same terminal behavior.